Hannah nitrate testing observation

[ScuttleBug]

I have had high nitrates over the maximum reading for the Hannah hr nitrate checker. Tried diluting the test by using half RO water and half tank water, still was over the maximum. Ended up diluting to 1 part tank water to 9 parts RO water. Reading was in the 40s, multiplied by 10 gave me 400. My tank is not dying and corals are all open just not growing. So I figured this was wrong. Mixed up some fresh salt water and did the same dilution and ended up getting 12.7 so 127, this seems much more reasonable. If anyone knows the reagent used and how the reaction works I am curious. Im assuming there is an ion in the saltwater that reacts with the reagent to compete with the nitrate? Also I figured out what’s causing the high nitrates. My phosphates were basically 0.0. I started dosing and have seen a coralline and macro explosion.

 

[taricha]

You'll also want to test just your dilution liquid to be sure you know what's in the 9 parts in 10.

 

[ScuttleBug]

I have tested both the RO water and the mixed water. The RO water tested 0.0 same with the fresh salt water mixed with the RO water. Just tried it again. Get well over 400 if I do 9 parts RO and 1 part tank water. 120 of 9 parts fresh salt water and 1 part tank water. Again all using the same source RO water. I test my RO water frequently because we have 20 ppm nitrates in the source tap water. Maybe it’s a buffer thing with sea water.

 

[Suohhen]

The Hanna checker uses the same zinc reduction and color comparison method as a few of the other nitrate test kits in the hobby. There are a few possibilities. The way zinc reduction works is to turn the nitrate into nitrite and then test for nitrite (first reagent does the reaction and the second is a dye) so obviously if there is already nitrite in the sample this can throw off the results. Hanna has a patented reagent called Nitraver 5 which reduces this to 1 reagent, however it is the same test. There could be an issue with calibration or just simply a defect to the unit. Or what I would say is most likely is that the reagent is defective. I have had many nitrate test kits in the past that would start reading super high when they got old or were defective in this way from the beginning.

 

[Dan_P]

I have had high nitrates over the maximum reading for the Hannah hr nitrate checker. Tried diluting the test by using half RO water and half tank water, still was over the maximum. Ended up diluting to 1 part tank water to 9 parts RO water. Reading was in the 40s, multiplied by 10 gave me 400. My tank is not dying and corals are all open just not growing. So I figured this was wrong. Mixed up some fresh salt water and did the same dilution and ended up getting 12.7 so 127, this seems much more reasonable. If anyone knows the reagent used and how the reaction works I am curious. Im assuming there is an ion in the saltwater that reacts with the reagent to compete with the nitrate? Also I figured out what’s causing the high nitrates. My phosphates were basically 0.0. I started dosing and have seen a coralline and macro explosion.

Test for nitrites.